Ricoh 28mm ltm focus problem on digital M

[doubledan]

I have a Ricoh GR 28 ltm lens, produced in limited numbers in the 1990s, which works very well with an M adapter on my film rangefinders. However, it seems to back focus on the digital Leicas, including M9 and M240. I consulted a tech at Nippon Camera, a reliable shop here in New York, and he said the lenses are perfectly adjusted but just don't focus right on digital cameras. Anyone know why this should be so? And if there's a solution?

I have the same issue, though less pronounced, with a Konica rf lens from the same era --the little 50mm f2.4 collapsible.

Dan

 

[lonemantis]

The discrepancy between focus on film vs. digital could be due to digital being more demanding of precise flange depth adjustment - there may be an error on film as well, but you're not seeing it due to film's lower resolution. (this was a big deal when the M8 first came out)

Since it's an LTM lens, one trick you could try would be buying a few different cheap LTM adapters, especially the no-name ones from China. These adapters are notorious for poor tolerances, which can often lead to backfocus being too long or too short. These adapters are usually around $10 each, so you might happen to find one that works with your particular lens.